Pyridoxal 5’-phosphate (PLP), the biologically active form of vitamin B6, is an essential cofactor for
multiple enzymes and involved in the synthesis and catabolism of neurotransmitter, homocysteine (HCY)
transsulfuration, and the metabolism of other amino acids, fats, and glycogen. Large surveys in the US
(NHANES) showed that B6 deficiency usually occurs in association with neurological abnormalities
including depression and cognitive dysfunction, anemia, impaired nutrient metabolism, steroid hormone
function, immune function. The dependence upon exogenous sources to maintain adequate levels of
Vitamin B6 in the body makes it clinically desirable to measure pyridoxal 5'-phosphate.